Copy amaflags to sip_pvt from peer during create_addr_from_peer

Copy amaflags to sip_pvt from peer during create_addr_from_peer

For whatever reason, we don't have a single function for copying data like this
from SIP peers to the SIP pvt. This patch adds the copying of amaflags to the
sip_pvt, but it would probably be worth discussing this function along with
the others that essentially just copy some amount of data from a peer to a
private.

(Closes issue ASTERISK-19029)
Reported by: Matt Lehner
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Merged revisions 352755 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 352756 from http://svn.asterisk.org/svn/asterisk/branches/10

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@352757 65c4cc65-6c06-0410-ace0-fbb531ad65f3